There are many benefits to small-incision sutureless cataract surgery, including faster stabilization of astigmatism in the early postoperative period, but few, if any, long-term studies have been conducted to assess this. In a recent study, researchers retrospectively assessed astigmatic changes over 10 and 20 years after small-incision cataract surgery.

Data was collected from patients who had undergone phacoemulsification and intraocular lens implantation through a 2.2mm to 2.4mm incision. Preoperative corneal and postoperative manifest astigmatism were converted to power vector notations: horizontal/vertical (J0) and oblique (J45) astigmatism components.

A total of 422 eyes of 422 patients were followed for 10 years with data collected before and at one month and one, three, five, eight and 10 years after surgery. The authors found a continuous against-the-rule astigmatic shift over time following surgery, as shown by a constant decline in the power vector notation J0 with an against-the-rule shift of 0.363±0.433D over 10 years. The change in against-the-rule astigmatism was 0.363D and 0.649D for 10 and 20 years, respectively.

These results are consistent with a previous study that reported against-the-rule astigmatic changes of 0.33D and 0.64D over a follow-up period of 10 and 20 years, respectively, after 4.1mm temporal incision sutureless cataract surgery in patients who were 61.8±6.0 years old at baseline. Another study reported a mean against-the-rule astigmatic change of 0.13D at five years in a normal adult population 50 years and older at baseline.

The study also showed that eyes that did not undergo surgery showed against-the-rule changes of 0.21D and 0.49D over a follow-up of 10 and 20 years, respectively, from a baseline age of 59.9±5.8 years.

In the subgroup analysis, conducted in 34 patients who were followed up for 20 years, J0 declined significantly by 0.649±0.576D over a 20-year follow-up period, while J45 did not. The postoperative changes in J0 and J45 were not significantly different between eyes with preoperative with-the-rule, against-the-rule or oblique astigmatism.

Between the results of the previous and current studies, the authors suggest these changes appear to reflect the natural course of corneal astigmatic changes that commonly occur with aging.

“The results of these previous and current studies indicate that long-term changes in astigmatism after small incision cataract surgery are attributable to the physiological against-the-rule astigmatic changes that commonly occur with aging,” the researchers explained in their paper on the study. “It seems that small incision sutureless cataract does not induce any additional long-term astigmatic changes in the sense of increasing the natural ATR shifts observed in eyes without the history of ocular surgeries.”